import { LightningElement, track, api } from 'lwc';

export default class App extends LightningElement {


    @track infoText;
    @track data = [];

    handleItemRemove(e) {
        this.infoText = e.detail.item.name
    }

    handleClickW(e) {
        this.data.push({ label: 'a ' + this.data.length, name: 'b' + this.data.length })
        this.redraw = true;
        this.infoText = 'Count:' + this.data.length;
    }
}

<template>
    <div class="slds-m-vertical_medium">
        <p>Info: <span class="slds-text-heading_small">{infoText}</span></p>
    </div>
    <div>
        <lightning-button label="Neutral" title="Neutral action"
        onclick={handleClickW} class="slds-m-left_x-small"></lightning-button>
    </div>


     <lightning-pill-container items={data} onitemremove={handleItemRemove}>
    </lightning-pill-container>

</template>